This seems way too niche. The main question is: how does the folding really help?
Seems like a tablet running macOS solves the issue. Have whatever inputs you want on the road (or none if you just use touch inputs) and then plug into a docking station at your desk. You could either use the tablet as your screen or as one of multiple monitors.
Unless I am missing something, the only point of a folding device is for a smaller footprint, but beyond pocket size, you're carrying a bag anyway. The folding doesn't make a lot of sense with virtual inputs. I don't think there's a large crowd of people touch typing without looking on virtual keyboards.
The other issue is size. Even a single 27" monitor folded in half is... large.
You have to find a space where someone wants a single machine, wants a single display when working at a desk, is all right with that single display being in a particular size range where folding it in half isn't ridiculous, and wants to also use this machine on the road.
Most people I know who use laptops professionally do not use them exclusively. They have a desk (or desks) with larger setups and in most cases are using displays much bigger that your scenario. Additionally, and I realize this is entirely anecdotal on my part, the handful of people I know who use their laptop exclusively... aren't doing anything I would consider "real" work of any kind.
Basically, someone has to really love getting by on like a 20-24" screen max and also using virtual inputs on a folding device. That seems like a ton of compromises for a very small group of people.
This may be anecdotal as well, but I know of plenty of people who almost exclusively use a single laptop for all their ['real'] work. A desktop is typically much more powerful than a laptop is (unless we're comparing an M1 MacBook to an M1 iMac); yet, by no means are today's laptops
under-powered. In fact, today, an M1 laptop is more powerful than plenty of people's existing desktops. There seems to me to be a growing trend of professionals ditching traditional desktops and instead choosing high-end portable devices, and the M1 switch is a further driver of this. At this point, the only people who badly need a Mac Pro or similar are those doing specific work that just happens to require more computing power — not necessarily that their work is any more serious than that of someone who primarily uses a laptop.
A tablet running macOS would be nice, but it would still just be a tablet. I think the interesting thing about a laptop that can unfold into a large tablet — a tablet which can also be attached to peripherals and then used as one large screen — is that it would provide more versatility than either a traditional laptop or a traditional tablet. Effectively, it can be used as all three: a tablet, a laptop, and a sit-down home computer. It may not be quite 27" when unfolded, but it could still be sizeable. Imagine a screen whose size is about equal to the surface area of a 16" MacBook Pro's screen + case/palm rest: it would be easily portable, when folded; large enough to be a desktop screen, when unfolded. I concede, though, that the aspect ratio would be quite odd... which I am sure would lead to Apple needing to put significant energy into coming up with a design for such a system. But, consider that two screens clamshell'd together won't necessarily have a footprint any larger than that of a traditional laptop.
Update: I've also shared my thoughts,
here, on the recently released patent describing a minicomputer built into an Apple keyboard. While this could contradict some of what I said, I think that such a product is a great idea as well — if but less useful than an unfolding laptop screen.